1. Field of the Invention
The present invention relates generally to an apparatus capable of detecting electromagnetic waves, and more particularly, to a battery-free electromagnetic leakage detector without power supply or battery.
2. Description of the Related Art
As the technology progresses through time, the high-technology products also keep progressing. People in the modern time have become more and more dependent on the high-technology products for convenience and their lives are full of electric/electronic products including high-energy appliances, such as electric stoves, microwave stoves, wireless communication products, etc.
In the daily living environment, the electric appliances are everywhere. However, the currents flowing in the circuit definitely generate electromagnetic waves which may be hazardous to health. Therefore, it is necessary to take precautions for detecting and preventing the electromagnetic waves from leakage. Although active electromagnetic detectors are commercially available for precise detection of the magnitude of the electromagnetic waves, they are expensive and inconveniently portable.
Among the prior art, there are other approaches of detecting the electromagnetic waves, like U.S. Patent Laid-open No. 2006/0289525 entitled “Microwave Leakage Indicator Card”, which disclosed that an antenna is employed for receiving the microwave energy and then such microwave energy is converted into thermal energy via a back-end circuit to further change the color of the proposed temperature sensitive color indicator for displaying the detection of the electromagnetic waves. Besides, Taiwanese Patent No. M357,670 disclosed a thin energy-saving security alert discoloring device for electromagnetic waves, in which an antenna resonant circuit detects the electromagnetic waves and converts them into magnetic energy to drive a magnetically discoloring material to discolor for displaying detection of the electromagnetic waves.